How to Backup Gmail or Move to a Google Apps Account

I recently had a client for whom we setup Google Apps so they could use Gmail, but using email addresses at their own domain. Once we got it setup, he wanted to know how he could personally move emails, labels, etc, from his current personal Gmail account, to his new Google Apps-based account on the company domain.

After a little searching I came across this excellent little free utility called Gmail Backup, which allows you to download your entire Gmail account to your local computer. Though intended for backup, it’s also a simple and effective way to migrate your Gmail account to a Google Apps mail account, or vice-versa.